The Phenomenon Of Emiliania Huxleyi In Aspects Of Global Climate And The Ecology Of The World Ocean

Abstract

Emiliania huxleyi (Lohmann) evolved from the genus Gephyrocapsa Kamptner (Prymneosiophyceae) of the coccolithophore family Naёlaerhadaceae. Over the past 100 thousand years E. huxleyi has acquired the status of the most ecologically predominant coccolithophore due to its remarkable adaptability to a variety of environmental conditions and interspecific competitiveness. E. huxleyi plays an important role in both the marine carbon system and carbon cycling between the atmosphere and ocean due to its ability to produce organic and inorganic carbon as well as to form massive blooms throughout the world ocean. This study examines both older information and recent findings to shed light on the current tendencies in the two-way interactions between E. huxleyi blooms and the immediate and global environment under conditions of climate change. The assembled knowledge has emerged from laboratory and mesocosm instrumental investigations, retrievals of satellite remote sensing data, machine learning/statistical analyses, and numerical simulations. Special attention is given to both the quantitative data reported over the last two decades on such interactions, and the only very recently appearing mid-term projections of E. huxleyi bloom dynamics across the world ocean. These blooms strongly affect the atmosphere and ocean carbon cycles. They reduce CO2 fluxes from by ~50% to ~150% as is documented for the North Atlantic, and on the global scale release particulate inorganic carbon as calcium calcite in the amounts assessed at 0.4 to 4.8 PgC/yr. At the same time, they are also sensitive to the atmospheric and oceanic state. This results in E. huxleyi blooms having an increased impact on the environment in response to ongoing global warming.

Different photosynthetic responses of haploid and diploid Emiliania huxleyi (Prymnesiophyceae) to high light and ultraviolet radiation

“…More importantly, E. huxleyi forms extensive blooms with a large number of cells, and these blooms cover up to 1.4 × 10 6 km 2 of the world ocean annually (Holligan et al 1993 ; Brown and Yoder 1994 ; Tyrrell and Merico 2004 ; Brownlee et al 2021 ). Several environmental factors, including low silicate contents, high carbonate saturation state, etc., are considered facilitative for the development of blooms (Tyrrell and Merico 2004 ; Zondervan 2007 ; Pozdnyakov et al 2021 ). However, high light conditions seem to be a crucial prerequisite for blooms (Tyrrell and Merico 2004 ; de Vries et al 2020 ).…”

“…At the sea surface or the water column surface, a high intensity of photosynthetically active radiation (PAR, 400–700 nm) is always accompanied by a high intensity of ultraviolet radiation (UVR, 280–400 nm), known as a stress factor damaging the protein and DNA of phytoplankton (Sinha and Häder 2002 ; Leunert et al 2014 ; Haney et al 2022 ). Depending on the scattering and absorption of seawater, UVR might penetrate through the water column to a depth of more than 20 m, where E. huxleyi is often observed and its blooms tend to occur (Nanninga and Tyrrell 1996 ; Falkowski and Raven 1997 ; Boelen et al 1999 ; Frada et al 2012 ; Jin et al 2013 ; Pozdnyakov et al 2021 ). E. huxleyi is thus expected to be exposed to UVR, especially if the vertical mixing of surface water is also considered (Jin et al 2013 ).…”